1. Field of the Invention
The present invention relates to a method of and apparatus for continuously crimping and cutting at least one continuous yarn.
2. Technical Consideration and Prior Art
When it is desired to process synthetic or artificial textile fibers, in the form of a mixture with natural fibers, it is necessary, since the latter fibers are crimped, to crimp the synthetic fibers, in order to improve the homogeneity of the mixture prior to converting it, generally to a yarn spun from fibers.
The crimping operation is carried out in a known manner on continuous filaments in the form of a tow. The cutting operation follows the crimping operation. Either a stuffing-box or two cogwheels, between which the tow passes, is generally used to effect the crimping operation. The crimping obtained is uniform, and the fibers are crimped in phase. However, it is often preferable to have fibers, in which the crimps are not in phase and are disordered.
The disordered crimping of filaments is preferably achieved by means of pneumatic processes such as those described, for example, in U.S. Pat. Nos. 3,373,470, 3,703,754 and 3,827,113 assigned to the company to which the instant invention is assigned.
According to these processes, at least one multi-filament yarn is introduced into an injecting device simultaneously with passing a hot fluid under pressure into the injecting device. Under the effect of this fluid, the filaments of the yarn become separated. The turbulence creates a phase displacement between the filaments, which are no longer parallel to one another. Further, under the effect of the fluid, the filaments are subsequently introduced into one end of a large tube of constant cross-section, which is open to the atmosphere at its other end, and is perforated laterally with orifices, through which a part of the fluid escapes. The remainder of the fluid pushes the filaments, which become stacked up inside the tube to form a piled-up wad.
It was possible to derive benefit from this piled-up wad, and to cut it and thereafter to collect the fibers obtained. This was the subject of U.S. Pat. application No. 436,911, assigned to the assignee of the instant invention, according to which, it is proposed to cut the wad, either at the outlet of the crimping tube or inside the crimping tube.
It has already been proposed, particularly in U.S. Pat. No. 1,983,326, to cut yarns continuously, while they are being wound up on a mandrel. In this patent, the yarns are wound around a heated mandrel, and are then cut from inside the mandrel by means of reciprocating knives, which cut the yarns that have been wound up. The hot mandrel makes it possible to fix the coiled shape of the yarns, and after cutting, to obtain loop fibers. However, this device is complicated, and the fibers obtained have uniform loops.